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JavaScript

var myString = '{"SecureZoneSubscriptionList": { "EntityId": 51350993, "Subscriptions": [{ "ZoneName": "FACCM    Membership", "ZoneId": "6460", "ExpiryDate": "9/5/2014 12:00:00 AM",    "SellAccess": true,  "CostPerPeriod": "0.1",  "CycleType": ""        }, ] } }';
var matches = myString.match(/"ExpiryDate":\s?"([^"]*)"/);
console.log(matches);
alert(matches[1]);